1. Field of the Invention
This invention is related to a charged particle detector and methods for fabricating and using the electron detector.
2. Description of the Related Art
In general, a Faraday cup is regarded as a simple detector of charged particle beams. A faraday cup typically includes an inner cup concentrically located within a grounded outer cup. Faraday cups are known for their large dynamic range and ability to function in a wide range of environments, including atmospheric pressure. Well designed and shielded Faraday cups have been reported to measure currents down to 10−15 A, corresponding to 104 charged particles per second. While electron multipliers are more sensitive, Faraday cup detectors provide quantitative charge measurements with high precision and stable performance. For instance, electron multipliers are susceptible to degradation over time due to sputtering of the electron conversion material, and the gain of these detectors can vary depending on the mass of the impending ions.
Faraday cup arrays designed for use in a mass spectrometer have been previously built which included an array of MOS capacitors formed on the interior of high aspect ratio deep etched trenches in n-type silicon. In those designs, the silicon between each cup served to electrically shield cups from their neighbors, enabling low signal cross-talk. Linear arrays of 64, 128 and 256 cups at pitches of 150 μm and 250 μm have been fabricated. The width spacing between the cups was typically limited to 50 μm. Detector arrays have been fabricated where for ion detection metal strip electrodes or MOS capacitors were used.
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